Mineral oil lubricating composition containing a copolymer of an alkyl ester of itaconic acid and an alkyl acrylate or methacrylate



Patented May 5, 1953 Mm ngln pin QNI N ESTER or 1 W iB T NG i MiQ S TQfi A QOPOLYMER OF AN ALKYL TACONIC ACID AND AN ALKYL ACRYLATE onMETHACRYLATE Thomas Stanford Tiltwilei; Elizabeth, J, as= Signor toStandard Oil Development Gmrlpan y; a corporation of Delaware NoDrawing. Application December at,- 1948, Serial No. 68,378

(on sea-56) A 4 Claims: 1

The present ii lviitiolirelates to. ccpelymers of unsaturated clibasicacid esters and their derivatives with acrylic esters and relatedcompounds. The present invention further relates to the use of polymericmaterials of this general type as ascitives; for lubricating oils and}analogous compositions, and to the formulation of oil compositions, andthe like containing said additives as new products of manufactiire. Theinvention further relates tothe processes for producing the products ofthe character referred to above.

It has been fennel, anti is the subject matter of the invention, thatalpha-methylene dicarboxylic acid esters readily copolymerize with.alpha,v beta unsaturated mono'carboii-jilic compounds to yield shearstable and thermally stable on soluble products which are particularlvaluable as lubricating oil acci'tives as viscosi ty: index im rcv'ersour sepressants, anti the like.

It is wellknown in theprior art that ifiini a l base lubricating oilsand, particularly, lubricatin'g' oils such as; those used in" the crankof automotive engines, have: serious limitations with respect to pourpoint and v ontymemperature relationships unless they are pi pared froiully s'elected materials or are iiitiiiifieri to iiii' prove-theirviscosity and/or'their pour characteristics-. The present invention has;as a er object; the production of animproved ad matreial for oils whiclris suitable both for irh proving the viscosity inde x' anal for icweniigthe ponr'point.

While reference is made above to lubricants for automotive crank cases,i/fvil-i be understoda that the iriirentron" has application to othertype lubricants and is applicable generally to were carbon oil fractionssuch as hydraulic oils and in some instances to synthetic oils which areemployed similarly to naturally occurring miera-l oil's.

An important object of this invention is to produce polymeric materialswhich are stable at high rates of shear and are stable when em: ployedin. internal combustion engines as a c'bnst-ituent of the lubricatingoil; A further'obj ect of this invention-is to produc apolymericmaterial which is useful for improving'the'visco'si'tytemperaturecharacteristics of oils Without excessi vel'y" increasing the viscositymembrane which may be; used in various hydrocarbon base stock's derivedfrom variousemceoils; s'uc'll as: parar finic; naphthe'nicy asphaltic"or mixed base: A still. further object is" to repare a material-whichpoints or ens u on repeated cycles as temperature change above and belowthe normal pour points. Many materials which are eiiective pour pointdepressers in lubricating oils, for example, become unsatisfactory afterbeing subjected to a large number of temperatur changes. This propertywhich is commonly referred to as pour instability is highlyobjectionable under many conditions where low temperatures areencountered and an object of this invention is to prepare materials andlubricating oils containing suchmaterials which are free from pourinstability.

As an important aspect of the present infven' tion, it has beendiscovered that excellent shear stable and thermally stable polymericlubricating oil additives may be produced by opolyiiieiizihgalpha-methylene unsaturated dicarboxylic acid esters, wherein theesterifying group contains 6 or less carbon atoms, with compounds havingthe formula R! Riff mint-t cs" wherein it is hydrogen or ai ialkylgroup; R is hydrogen or a halogeir, R is hydrogen; a halogen or an alkylgran an it? is 1' alkyl; al-i'c'yclic aranryi or alpl yl grasp semia-'irig abreast 8 carbon atoms; In general, when R anti R" are alkyl, itis prefer that they be relatively small, for exam le; methyl, ethyl;iopyi isopropyl; etc. Among the cont-petites of ty are esters of acrylicacid; methac'rylic acre, alpha-chief" acrylic acid, crotonic' acid,alpha clilor crotonic' acid, beta chlor' crotch-id acre and mixturesthereof. The alpha-methylene dicarboxylic acid esters which arecopolymerized with the alpha, betaunsaitura terl compounds have thefollowing general folniuli 2 cl n c-o o o R tooR' aralkyl' or alphyl'group I usuallycontaining no e 131 6 carbon ate" Examples fthese es 1 'spi es'e -at 1east=one- 1011s chain hydrocarbon radical tailfiiiigfromabout 8 to" about 2'4" carbon atoms! Tliese long chains are supplied bythe alpha-beta unsaturated compound. The presence of these relativelylong chains is of value in providing oil solubility and also forimparting desirable propertie to the copolymer. For the production ofpour depressants, it is essential that there be side chains containing10 or more carbon atoms. These long chains may be supplied by thealcohols which are used to prepare the esters of the alpha-betaunsaturated compounds.

For the production of unusually effective V. I. improvers, it isnecessary to have short side chains such as methyl, ethyl, butyl, etc.present in the copolymer in addition to the long side chains necessaryto give oil solubility. These short side chains are supplied by thealphamethylene dicarboxylic esters. It has been found that copolymerscontaining methyl side chains are usually more effective V. I. improversthan similar copolymers containing ethyl, butyl or longer side chains,and that, in general, the V. I. improving potency of similar copolymersdecreases as side chain length, as supplied by the alpha-methylenedicarboxylic ester, is increased.

This is illustrated as follows:

3.6 Wt. Percent Copolymer in Oil B l C 1 er ODD ym Viscosity, S. U.S./210 V. 1.

Dimethyl Itaconate, 2% 147 Cs x0 Acrylate, 98% 64 0 Diethyl itaconate,4% 62' 7 146 62.8 145 Cs 0x0 Acrylatc 63. 4 143 1 Oil B=lubricating oilhaving 45 S. U. S. viscosity at 210 F. and 115 V. I.

One commercially available alcohol mixture suitable for the preparationof the esters may be obtained from the hydrogenation of coconut oil.Such a product is sold under the trade name Lorol and is a mixture ofsaturated straight chain alcohols ranging from 10 to 18 carbon atoms andhaving a major proportion of lauryl alcohol which has 12 carbon atoms.Other related products are made by separating this material, which maybe considered as a crude mixture, into several difierent fractionshaving a relatively higher proportion of the higher, lower, or mediumconstituent thereof. The composition of Lorol per se and relatedproducts, Lorol B and Lorol R, is approximately as follows:

Compositions of Mixtures of Commercial Alcohols Lorol Lorol B Lorol Rercent. 4 3 1 .d0 55. 46 85 "110--.- 22. 5 24 13 .do.- 14 1 d0 4 17Atoms. 12. 8 13. 5 12. 2

the synthesis of hydrocarbons from carbon monoxide and hydrogen may alsobe used. Primary aliphatic alcohols are preferred, although secondaryalcohols may be employed.

Also, alicyclic alcohols such as cyclohexanol. methylcyclohexanol andhydrogenated alkyl phenols, aralkyl alcohols such as phenylethanol, andalphyl alcohols such as alkylated phenols, cresols, etc., can beemployed. The above-mentioned alcohols may contain functional groupssuch as halogen, NHz, CN, NOz, OR, -O(CH2)n-OR, etc., provided they donot interfere with copolymerization or render the copolymer insoluble.Whereas straight chain and slightly branched aliphatic primary alcoholsgive excellent results and are therefore preferred, the other types ofalcohols and their derivatives mentioned above can be employed forpreparing the ester monomers which are copolymerized according to theinvention. It will be understood that mixtures of alcohols of the sametype or of different types can be employed. In the case of estersprepared from the alpha-methylene dicarboxylic acid, mixed esters suchas methyl decyl itaconate can be copolymerized with the alpha,beta-unsaturated monocarboxylic compound with good results.

Half esters of alpha-methylene dicarboxylic acids may also be used inthe preparation of copolymers. The resulting products contain freecarboxyl groups which may be used as such or which may be neutralized byreacting with an alcohol, a primary or secondary amine or with ammoniaor with a metal-containing compound to obtain an esterified, amidized orimidized product or an ammonium or a metallic salt.

Various conditions of copolymerization may be used in this inventioninvolving either bulk or emulsion techniques. In bulk polymerizationdiluents may or may not be used. Temperatures may vary from 25 C. to 150C. for periods ranging from 5 minutes to hours and in the presence ofvarious types of catalysts such as benzoyl peroxide, t-butylhydroperoxide, cumene hydroperoxide, and other peroxides, aluminumchloride, boron fluoride, activated clays, ultraviolet light, and thelike.

The oil solubility of the finished copolymeric material is governed to aconsiderable extent by the ratio of the alpha methylene dicarboxylicesters, which supply short side chains to the copolymer, to the alpha,beta unsaturated monocarboxy esters, which supply long side chains tothe copolymer, employed in the copolymerization reaction. Examples ofapproximate maximum ratios giving copolymeric materials soluble in alubricating oil consisting of 94% solvent extracted Mid-Continent stockand 6% solvent extracted bright stock are as follows:

I II

Acrylate Copolymers of higher ratios of short chain esters to long chainesters may be soluble in other types of lubricating oil stocks.

The average molecular weight of the finished polymeric material shouldnot be less than 1,000 or more than 50,000. The preferred range is 7,000to 17,000 being especially preferred.

The copolymers which are produced according to this invention not onlyare-suitable pour depressants and viscosity index improvers but also arerust inhibitors, detergents, and generally improve the condition of theengines in which they are used. These copolymers may also be used incompounding greases, waxes, and the like, and may-also be used inconjunction with other additive materials such as pour de pressants,viscosity index improyers, rust inhibitors, detergents, extreme pressureagents, dyes, and the like.

The invention will better be understood from the specific examplesdescribed hereinafter which are illustrative only and are not to beconstrued as limiting the scope of the applicants invention.

EXAMlE-LE I To g. of dimethyl itaconate were added 180 g. of octyl,decyl methacrylate (a mixture of octyl and decyl methacrylates) and 164g. of a white oil having a S. U. S. viscosity at 210 F. in a 3-literstirring flask contained in an oil bath. The mixture was then heated for48 hours at 70 C. in a nitrogen atmosphere adding 1 gram of benzoylperoxide at the start and 1 gram of benzoyl peroxide after heating themixture for 1 hour. A clear homogeneous copolynier was obtained whichwas blended to 20% com centration in a lubricating oil having aviscosity of 43-44 S. U. S. at 210 F. and this oil concen tration wasemployed directly as a V. 1. improver.

EXAMPLE II To 100 g. of climethyl itaconate were added 900 g. of octyl,decyl methaerylate and 755 g. of a .1

white oil having 43 S. U. S. viscosity a 210 15k, in a 3-liter stirringflask contained in an oil bath. The mixture was then heated for 27 hoursat 70 C. in a nitrogen atmosphere, adding 5 grams of benzoyl peroxide atthe start and 5 grams of benzoyl peroxide after heating the mixture for1 hour. A clear, homogeneous copolymer was obtained which was blended to4.0% concentration in a mineral lubricating oil having 43 .4 S. U. S.viscosity at 210 F. and this oil concentrate was employed directly as aV. I. improver.

EXAMPLE III To 0.2 grams of dimethyl itaconate were added 9.0 grams ofoctyl 0x0 acrylate, 10.0. grams of a white oil having a 43 S. U. S.viscosity at 210" F. and 0.10 gram of 100 mesh benzoyl peroxide in a cc.test tube. The tube was flushed with nitrogen, stoppered, agitated toeffect complete solution, then heated for 30 hours at 70 C. in an oilbath, A clear, homogeneous copolymer was obtained which was blended to20% com centration in a lubricating oil. having a viscosity of l3a44 S.U. S. at 210 F. and this oil com centration was employed directly as aviscosity index improver. The octyl alcohol from which the acrylate wasprepared was made by the 0x0 reaction in the presence of a cobaltcatalyst of CO, hydrogen and a C7 olefin fraction, obtained from thepolymerization of C3-C4 refinery gases in the presence of phosphoricacid catalyst, forming octyl aldehyde which was then hydrogenated to thealcohol.

EXAMPLE W copolymer of 1.7 g. of dimethyl itaconate with 9.3 g. ofdecyl. acrylate was prepared in a similar manner to Example III,employing 9.0 g. of white oil diluent and 0.11 g. of mesh benzoylperoxide.

EXAMPLE V A copolymer of 2.0 g. of dimethyl itaconate with 8.0 g. oflauryl acrylate was prepared, in' a similar manner to Example III,employing 7.0 g. of white oil diluentand 0.10 got 100 mesh benzoylperoxide.

EXAMPLE VI A copolymer of 3.2 g. of dirnethyl itaconate with 12.8 g. ofLord R aeryl-ate was prepared in a similar manner to Example III,employing 11.1 g. of white oil diluent and 0.16 g. of 100 mesh benzoylperoxide. This copolymer was also useful as a pour depressant.

EXAMPLE VII A copolymer of 0.4 g. of diethyl itaconate with 9.6 g. ofoctyl 0 x0 acrylate was prepared in a similar manner to Example III,employing 10.0 g. of white oil diluent and 0.10 g. of 100 mesh benzoylperoxide.

EXAMPLE VIII S. U. S. 3.6 Wt. Percent Via/210 F., Copolymer in Oil B C20 Wt.

opolym'er Percent Copolymer S. U. S. V I

in Oil A Via/210 F.

Dimethyl Itaconate, 10% Octyl, dccyl Methacrylate, 90%.-. 323 61. 4 14 7Example I Dimethyl Itaconate, 10%., Octyl, decyl Methacrylate, 90%." 35262. 3 149 Example II Dimethyl Itaconate, 2% Octyl 0x0 Acrylate, 98% 43364. 0' 147 Example 111 Dimethyl itaconate, 15% Deeyl Acrylate, 85% 66074.1 154 Example IV Dimethyl Itaconate, 20% Lauryl Acrylate, 80% 60168.1 152 Exam e V Dimethyl Itaeonate, 20%.., Loro'l R acrylate, 80% 40163. 8 150 Example VI Diethyl Itaconate, 4%. Octyl 0x0 Aerylate, 96% 37362. 7 146 Example VII Dibutyl Itaconate, 5%

362 63.4. 1.43 566 '71. 7 1&7 335 66.1 141 6 72- .14

Oil Aso1vent extracted lubricating oil having 43-44 S. U. S. vis. at 210F., 112 V. I.

Oil B-solvent extracted lubricating oil having 45 S. U. S. vis. at 210F., 115 V. I.

The following table illustrates the pour depressing properties ofcopolymers prepared according to this invention.

Oil C-conventinally refined Pennsylvania 180 Neutral.

Oil Dso1vcnt extracted Mid-Continent +Bright Stock-S. A. E. 10 grade.

The following tables illustrate the superior polymer stabilitycharacteristics of copolymers prepared according to the presentinvention as compared to the stability characteristics of other typemethacrylate-itaconate ester copolymers and 'sentially of a majorproportion of a mineral oil base stock and a small but viscosity indeximproving amount of a copolymer of dimethyl itaconate and a compoundhaving the formula wherein R is selected from the class consisting ofhydrogen and a methyl group and R is selected 10 from the classconsisting of the alkyl group containing from 8 to 24 carbon atoms.

3. A lubricating oil composition consisting essentially of a majorproportion of a mineral oil base stock and a small but viscosity indeximproving amount of a copolymer of dimethyl itaconate and mixtures ofoctyl and decyl methacrylate.

4. A lubricating oil composition consisting essentially of a majorproportion of a mineral oil a current commercial V. I. improver in bothbase stock and a small but viscosity index imlaboratory tests andautomotive enging tests.

proving amount of a copolymer of 1 mol of di- Polymer breakdowncharacteristics [McIntype pump testJ] Used Oil 4 Hr. New 011 Sample Vis.20% Copolymer 3 5 2 Wt LPercent perass, is. 011 A cent Visi, 210 V. I. Lasslin F" Copol. Based on Polymer Dimethyl Itaeonate, 10% Octyl, decylMethacrylate, 90%. 323 2. 75 75. 8 122 2. 0 16 D 17? t 8 7 ecy acona e,0 Methyl Methacrymtg 20% h 356 3.40 76.1 134 7.0 39 Commercial V. I.Improver X 651 2. 05 77.0 123 4.8 31

1 Oopolymer oil blend circulated through McIntyre gear pump at 200 F.and 1000 p. s. i. g.

Polymer breakdown characteristics [32 hr. Chevrolet engine test] What isclaimed is: 1. A lubricating oil composition consisting essentially ofa. major proportion of a mineral oil base stock and a small butviscosity index improving amount of a copolymer of an alkyl ester ofitaconio acid wherein the esterifying group .contains from 1 to 4 carbonatoms and a compound having the formula wherein R is selected from theclass consisting of hydrogen and a methyl group and R is selected fromthe class consisting of the alkyl group containing from 8 to 24 carbonatoms.

2. A lubricating oil composition consisting csmethyl itaconate and 0.1to 2.0 mols of mixtures of octyl and decyl methacrylate.

THOMAS STANFORD TUTWILER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,020,714 Wulff Nov. 12, 1935 2,091,627 Bruson Aug. 31, 19372,220,855 Slagh Nov. 5, 1940 2,279,881 DAlelio Apr. 14, 1942 2,279,883DAlelio Apr. 14, 1942 2,366,517 Gleason Jan. 2, 1945 2,375,516 Blair May8, 1945 2,422,881 Blair June 24, 1947

1. A LUBRICATING OIL COMPOSITION CONSISTING ESSENTIALLY OF A MAJORPROPORTION OF A MINERAL OIL BASE STOCK AND A SMALL BUT VISCOSITY INDEXIMPROVING AMOUNT OF A COPOLYMER OF AN ALKYL ESTER OF ITACONIC ACIDWHEREIN THE ESTERIFYING GROUP CONTAINS FROM 1 TO 4 CARBON ATOMS AND ACOMPOUND HAVING THE FORMULA